Method of testing materials



Dec. 13, 1927. I 1,652,525

w. HAHNEyIANN El AL METHOD OF TESTING IATBRIALS Mafia KW;

Patented Dec. 13, 1927.

WALTER HAHNEMANN, OF

KITZEBERG, NEAR KIEL, AND HEINRICH EEGHT, OF 'KIEL,

GERMANY, ASSIGNORS T0 SIGNAL GESELLSCHAFT MIT BESGHBANKTEB HAFTUNG,

OF KIEL, GERMANY.

METHOD OF TESTING -MATEBIALS.

Application filed January 29, 1923, Serial no. 615,684, and in Germany Januaryflo, 1922.

The invention relates to a method of test- 'ing materials, such for example as that explained in application Ser. No. 494,575,

which consists in subjecting a test-piece of the material to be tested to alternatmg stresses, the

test-piece being an elastic portion of a vibratory structure and the vibratory structure vibrating in its natural frequency.

way and in short time of observation the values for calculating the elastic properties of the material under test.

The invention combines with mentioned method piece to alternating the before of subjecting the testloads or stresses an observation in connectlon with the temperature of the test-piece.

Other particular may be explained features of the invention in connection with the drawings in which:

Fig. 1 shows an arrangement for testing materials according to the invention, and

Fig. 2 a curve of the difierent temperasame observatlonls repeated. In this way tures of the test-piece,

ing amplitudes of depending upon varythe vibratory structures.

In Fig. 1 the test-piece is represented by the rod 1,

mass 8 and the smaller mass 2 of-a vibratory structure comprisin mass 3 and an elastic memb besides another larger consists of an elastic rod 5 concentrically situated within an elastic being connected to vto the free end of which is connected. to the larger mass The smaller mass of an electro-magnetic which is represented by the vibratory structure citing coil 7 'fed by the alternating our of the alternating current generator 14.

mass 8 is mounted upon largeand heav rolls or balls 9 or tube 6, the rod the smaller mass 2 and the tube 6, the other of 3. 2 is formed as armature system the field of t e largeranass 3 of together witdran ex- The the purpose to enable the test-piece to expand on becoming hea without being bent.

The test-piece 1 11 preferably rubber or the for instance air, water \or oil.

leadings 12-a'hd'13 11 and an opening of yielding material such like and containing is surrounded by a bag as a fluid as Two feeding are connected to the bag 15 serves for the purpose.

er 4. The latter to introduce a thermometer 16. The fluid in the bag 11 may be caused to flow; it serves for cooling the test-piece and for enabling the operator to hold constant the temperature of the test-piece during observing. Measuring instruments 17, 18 inthe electrical circuit and a micrometer screw 19 connected to the masses of the vibratory structure enable the operator to observe the feeding current, the load applied to the testpiece and the amplitude of motion of the mass 2 of the vibratory structure, i. e. the amplitude to which the test-piece is subjected. i

Fig. 2 shows a diagram of the temperature poii1ts20 to 24: inclusive of the diagram are found. Finally the point 25 is obtained at which the temperature rises very rapidly m ert d between a large and heavy and no longenattams a constant value but of the. test When the point knows that the load limit for under test has been reached.

piece occurs. the observer the material The temperature may be measured in any reiittwo elastically connected masses; causing the said'vibratory structure to vibrate in its nat-.

ural frequency, and observing the tempera ture developed in the test-piece by such vibration.

- w2. A method of testing materials comprising employing a test-piece a's an elastic portion of a vibratoryv structure formed of two elastically connected -masses; causing the said vibratory structure to vibrate in its natural frequency and at difierent amplitudes, and observing the temperature de- 25 is found,

veloped in the test-piece at each amplitude when the temperature attains a constant value.

3. Amethod of testing materials comprising employing a test piece as an elastic portion of a vibratory structure formed of two elastically connected masses, causing said vibratory structure to vibrate in its natural frequency, varying the amplitude of the vibrations, and observing the temperature piece at each amplitude tion of a vibratory structure formed of two elastically connected. masses, causing said vibratory structure to vibrate in its natural frequency at a certain amplitude, increasing the amplitude, and observing the effect 'of the increase in amplitude on the temperature of the test piece. p

5. In apparatus for testing materials, a vibratory structure formed of two elastically connected masses having a test piece forming an elastic portion thereof, means for causing said vibratory structure to vibrate in its natural frequency, means for varying the amplitude cat the vibrations, and means for observing the temperatures developed in the test piece by said vibrations.

6. A method of testing materialsacomprismg employing a test piece as an elastic portion of a- Vibratory structure formed of two elastically connected masses, causing said vibratory structure to vibrate 1n 1ts natural frequency at a certain amplitude, observing the ultimate constanttempera-ture attained by the test piece at said amplitude, and increasing the amplitude and observing the ultimate constant temperature attained at each increased amplitude until the point of rupture is approached where the temperature does not attain a constant value but rises rapidly.

7. A method of testing materials, comprising employing a test piece as an elastic portion of a vibratory structure formed of two elastically connected masses, maintaining said test piece submerged in a liquid, causing said vibratory structure to vibrate in its natural frequency at a" certain amplitude, observing the ultimate constant temperature attained by the test piece at said amplitude, and increasing the amplitude and observing the ultimate constant temperature attained by the test piece at each increased amplitude until the point of rupture is approached where the temperature does notattain a constant value but rises rapidly.

8. I11 apparatus for testing materials, a vibratory structure formed of two elastically connected masses having a test piece form ing an elastic portion thereof, means for maintaining said test piece submerged in a liquid, means for causing said vibratory structure to vibrate in its natural frequency, means for varying the amplitude of the vibrations, and means for observing tlie tem 'eratui-es developed in the test piece by sai vibrations. I

In testimony whereof We aflix our signatures.

WALTER 'HAHNEMANN. HEINRICH HECHT. 

